1. Field of the Invention
The present invention relates generally to hand tools for cutting various articles, and more specifically to a cutting tool including guide means for cutting or scoring across the length and width of a drywall sheet or board. The present tool includes an adjustably installable cutting blade body for installation on a guide in one of two mutually normal orientations to permit cutting or scoring in two mutually perpendicular axes.
2. Description of the Related Art
The use of gypsum wallboard or drywall has become the most common means of finishing the interior structure of most building structures. The installation and finishing of drywall boards or panels takes relatively little time for experienced workers, and provides a smooth surface for further finishing. Cutting drywall panels to size remains one of the more labor intensive aspects of working with the material, due to the different tools generally used in the measuring, marking, and cutting operations.
Generally, the cutting of drywall panels to any given shape or size involves about the same number of steps and time, with the panel being measured and marked for the cut, a straightedge aligned with the mark(s), and a separate cutting or scoring tool being drawn along the mark, as guided by the straightedge. The board is then broken along the scored line to separate the core material along the scored line, and the uncut backing paper is cut through to separate the two panels. This procedure is applicable to both non-rectangular and rectangular panels.
Yet, due to the rectangular configuration of most interior walls and surfaces, most drywall panel cuts are orthogonal and result in rectangular panels of various sizes. Even though forming such rectangular panels should be a relatively straightforward process, the same relatively involved procedure is used as for other panel shapes, resulting in considerable time spent on relatively simple configurations. Also, when the interior of a structure is constructed, the walls are nearly universally a single predetermined height. If this height is different than the length of a standard drywall panel, then the panel must be cut (or an additional piece added) to complete the coverage of the wall. It will be seen that each panel must be cut exactly the same, yet the measuring and cutting process conventionally involves the same number of steps and time for each cut, as for a series of different cuts to form different sizes and shapes of panels. The time spent conventionally in making a series of identically configured panels, adds considerably to the time and expense required for such work.
Accordingly, a need arises for a drywall cutting tool which simplifies the layout of orthogonal cuts to drywall panels. The present tool essentially comprises a T square, with the elongate blade of the square always remaining parallel and perpendicular to the edges of the rectangular board when the crossmember is aligned along one edge. The removable cutting body may be turned in one of two mutually orthogonal directions (four positions), so that the cutting blades are always aligned parallel and perpendicular to the edges of the board, thus guaranteeing a straight and true cut every time. The present tool requires only measuring and marking the board and properly aligning the guide, with the present tool being used for both measuring and guiding the cutting or scoring blade.
A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 4,956,919 issued on Sep. 18, 1990 to James P. Granger, titled xe2x80x9cDrywall T-Square,xe2x80x9d describes a device which is not strictly a T-square, due to the relative movement and disassembly of the two blades from one another. One rule is fixed relative to the drywall panel, with a second relatively movable rule having a series of lateral slots therethrough. A conventional utility knife is inserted through the desired slot and the movable rule is drawn over the panel, with the slot through which the knife blade extends, acting as a guide. The knife used with the Granger guide cannot be positioned for orthogonal cuts; the entire assembly must be repositioned along a perpendicular edge of the board.
U.S. Pat. No. 5,083,375 issued on Jan. 28, 1992 to Larry Helm, Sr., titled xe2x80x9cDrywall Cutting Device,xe2x80x9d describes a T-square like device in which the lower portion of the stem of the device may telescope for extension as required. Two separate tracks are provided, with the cutting head being slidably affixed to the two tracks of the extension and extending thereacross. The device uses a single conventional knife blade, rather than the spaced apart dual roller blades of the present drywall cutting tool. The Helm, Sr. tool is relatively flexible in comparison to the present tool, due to the relatively narrow telescoping arms of the Helm, Sr. tool and their spacing. The positioning of the cutting elements of the present tool outside the channel of the stem portion of the T, results in greater rigidity and more accuracy in forming a cut.
U.S. Pat. No. 5,231,764 issued on Aug. 3, 1993 to Kenneth Chang, titled xe2x80x9cCutter For A Plasterboard Sheet,xe2x80x9d describes a cutting device which clamps removably to a conventional T-square. The device is relatively simple, and thus has many limitations in comparison to the present drywall cutting tool. The knife holding body secures to the stem of the T-square in only one direction, with the knife blade always oriented normal to the stem of the square. Thus, the Chang device must be moved to a perpendicular second edge of the drywall sheet or board, in order to make a cut parallel to that edge or perpendicular to the first edge. Only a single conventional utility or drywall knife blade is provided by Chang, as compared to the dual spaced apart roller cutting elements of the present drywall cutting tool invention.
U.S. Pat. No. 5,265,342 issued on Nov. 30, 1993 to Joseph D. Lang, Jr., titled xe2x80x9cDrywall Cutting Tool,xe2x80x9d describes a device having a relatively short edge guide for sliding placement along one edge of a drywall sheet, with a rod adjustably extending from the guide. A cutting tool is secured to the end of the rod. The relatively short edge guide permits the guide to rock at least slightly, thus resulting in the cutting tool holding rod moving arcuately somewhat relative to the guide edge of the drywall sheet. The cutting tool cannot be rotated relative to its attachment to the rod. All cuts are made parallel to the movement of the guide along one edge of the board, thus requiring the tool to be moved to a perpendicular edge of the board for a cut perpendicular to the first edge. Only a single conventional cutting blade is provided.
U.S. Pat. No. 5,471,753 issued on Dec. 5, 1995 to Bernardo M. Rodrigues, titled xe2x80x9cCombination T-Square And Cutter,xe2x80x9d describes a square with a stem blade having a relatively wide slot along its center, with a knife holder adjustably riding in the slot. The holder cannot be turned ninety degrees in the slot, due to the provision of locking extensions only in opposite edges of the holder, which engage cooperating notches on each side of the slot of the stem of the square (column 2, lines 44-47). Thus, the device is only capable of making cuts perpendicular to the slotted stem portion of the device; the entire device must be relocated for perpendicular cuts. Moreover, the device includes only an open saddle for holding the knife, with the operator being required to hold the knife in place, unlike the present invention.
U.S. Pat. No. 5,600,892 issued on Feb. 11, 1997 to Glenn H. Peugh et al., titled xe2x80x9cDual Side Drywall Panel Cutter,xe2x80x9d describes a tool in which dual opposed arms extend downwardly from a single edge guide component, with each arm carrying a cutting blade. The device provides simultaneous cutting of the backing on opposite sides of wallboard material, when the two blades are positioned directly opposite one another. The cutting plane of the blades is fixed normal to the elongate axes of the two arms, and cannot be turned to make a cut parallel to the arms, as provided by the present cutting tool invention. While dual blades are provided by Peugh et al., they are on opposite sides of the sheet, rather than providing dual scoring action on a single side of the sheet.
U.S. Pat. No. 5,720,104 issued on Feb. 24, 1998 to Mark Decker, titled xe2x80x9cDrywall Sheet Trimmer,xe2x80x9d describes a relatively complex device providing simultaneous cutting on opposite sides of a sheet, somewhat like the device of the Peugh et al. ""892 U.S. patent discussed immediately above. The Decker device uses a complex rack and pinion mechanism for positioning the cutting elements relative to the edge of the sheet, as Decker uses the device only as a trimmer for trimming the edges of the panels, rather than for making cuts spaced well away from the edges, as provided by the present invention. The Decker device is impractical for such widely spaced cuts, due to the time required to readjust the rack and pinion mechanism over a relatively large distance. The orientation of the cutting blades is fixed relative to the slide, unlike the present drywall tool.
U.S. Pat. No. D-376,988 issued on Dec. 31, 1996 to Anthony T. Bruno, titled xe2x80x9cCombination Cutting Gauge And Guide,xe2x80x9d illustrates a generally L-shaped square, with the two legs of the design being fixed relative to one another. An arcuately movable arm is apparently depicted, but no slidably adjustable cutting tool body nor cutting blade means is shown. The design does not appear to be capable of making cuts parallel and perpendicular to a given edge of a board, at least at any of a series of different distances from that edge, as can the present invention.
U.S. Pat. No. D-406,537 issued on Mar. 9, 1999 to Merle L. Sharp, titled xe2x80x9cDrywall Cutting Guide,xe2x80x9d illustrates a pair of mirror image embodiments, with each comprising a long pole with a handle normal thereto and a knife carrier attached to one end of the pole. No means of securing the device to hold it parallel or perpendicular to one edge of a drywall sheet, is apparent from the drawings of the Sharp design patent.
British Patent Publication No. 111,579 accepted on Dec. 6, 1917 to Peter Milliken, titled xe2x80x9cImprovements In Instruments For Geometrical Drawing,xe2x80x9d describes a T square device with a slidably adjustable guide along the stem of the T. Holes are provided in the head of the T and in one side of the guide for a pencil or marking instrument, but no means is provided for the attachment or holding of a cutting blade or blades. In any event, the side view clearly shows that the stem and head of the T are coplanar with one another, and thus there is no way to hook the head of the T along the edge of a board, as is required with the present cutting tool.
Italian Patent Publication No. 513,079 published on Feb. 3, 1955 to Carlo Simonetta illustrates an elongate rule having an adjustably positionable roller and a cutting blade carrier or body affixed to one end thereof. No crossmember or head normal to the rule is provided, for holding the rule in a perpendicular orientation to one edge of the board for making a cut parallel or perpendicular thereto, as provided by the present cutting tool. Moreover, no means is apparent for turning the tool to make cuts parallel to the rule, as provided by the present invention.
Finally, British Patent Publication No. 2,203,839 published on Oct. 26, 1988 to Ture A. Ljungberg et al., titled xe2x80x9cCombination Of A Measuring Tool And A Sharp-Edged Tool,xe2x80x9d describes a method of securing a conventional drywall or utility knife to a conventional retractable tape measure, by inserting the hook end of the tape into the gap between the handle and blade of the knife. No cross head is provided for holding the device perpendicular or parallel to one edge of a sheet of material, and in any event, the flexible tape does not provide the required rigidity of the present cutting tool. Moreover, no means is provided for adjustably positioning the cutting tool at any point along the tape other than at its extreme end, whereas the cutting body of the present tool is adjustably positionable and may be turned ninety degrees relative to the rule to which it is secured, for parallel and perpendicular cuts.
None of the above inventions and patents, either singly or in combination, is seen to describe the instant invention as claimed.
The present invention comprises a drywall cutting tool for making cuts parallel or perpendicular to a reference edge of the drywall sheet or board, without repositioning the tool to a second edge for the second cut. The present tool essentially comprises a T square type instrument, with the head or crossmember and the stem of the T being immovably affixed to one another. A cutting blade body is slidably affixed to the stem of the T, through an elongate slot in the stem. A mechanism is provided for turning the cutting body relative to the stem, so the two roller blade cutting elements are either parallel or perpendicular to the stem, as desired.
For making a cut parallel to the reference edge along which the head of the T is resting, the cutting body is turned so the blades are parallel to the T head and locked to the stem at the desired distance from the head to produce a cut along the desired line. The entire assembly is then slid across the sheet with the head of the T acting as a guide along the reference edge of the sheet or board, to produce the desired cut.
For cuts perpendicular to the head of the tool and reference edge of the board, the cutting body is turned so the blades are parallel to the stem of the tool, i.e., perpendicular to the crossmember or head, and the body is loosened in the slot of the stem. The tool is positioned with the cutting blades along the desired cutting line and held immovably in place relative to the board, and the cutting body is slid along the stem of the tool to produce the desired cut.
Accordingly, it is a principal object of the invention to provide an improved drywall cutting tool for forming cuts in drywall sheet material, either parallel or perpendicular to a reference edge of the material along which the tool is placed.
It is another object of the invention to provide an improved drywall cutting tool essentially comprising a T square, with a head serving as a guide for the tool along a reference edge of a drywall panel and with a stem immovably affixed to the head of the T.
It is a further object of the invention to provide an improved drywall cutting tool which stem includes a cutting element body slidably affixed thereto, through an elongate slot in the stem.
An additional object of the invention is to provide an improved drywall cutting tool which cutting body is adjustably positionable relative to the stem portion of the tool, to position the cutting axis of the cutting body either perpendicular or parallel to the reference edge of the drywall sheet as desired.
Still another object of the invention is to provide an improved drywall cutting tool which cutting body includes a pair of spaced roller cutting blades, with the two blades straddling the stem of the tool when cuts parallel to the reference edge are made.
It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become apparent upon review of the following specification and drawings.